With rapid development of industries, fossil fuels are gradually exhausted. In addition, the greenhouse effect and the problem of gas emission attract global concerns daily. The stable supply of energy has become a major subject worldwide. In comparison with traditional coal, natural gas, or nuclear power, solar cells do not consume non-renewable resources. Instead, they convert directly solar energy into electricity by the photoelectric effect. Thereby, no greenhouse effect gases, such as carbon dioxide, nitrogen oxides, and sulfur oxides, and pollutant gases are produced. By reducing dependence on fossil fuels, a safe and autonomous power source is provided.
In a renewable power generating system, solar energy has the advantage of high environmental friendliness and ease of installation. Besides, its technology has become mature for commercialization and national programs are provided for promotion. Nowadays, it has become the major choice of advanced countries for developing distributed power system.
Nevertheless, solar cell technology still needs to be improved in many ways for enhancing its stability and lifetime or reducing its cost. Because a solar cell module is composed of many solar cells, when a single or a few solar cells is aged, damaged, sheltered by leaves or accumulated snow, or partially sheltered caused by installation orientation different from the other modules for matching the terrain or outer-wall structure of a building, the hop-spot effect occurs at the portions without illumination and hence resulting in thermal damages. This effect can severely damage solar cells. In addition, part of the energy generated by the solar cells with illumination might be dissipated by the cells without. For solving the problem, both electrodes of the output end of the solar cell assembly are connected with a bypass diode.
The function of the bypass diode is that when the solar cell appears the hot-spot effect and cannot generate power, the bypass diode can make the currents generated by the other solar cells flow thereby and thus enabling the solar cell power generating system to continue power generation. A problem occurring at a certain solar cell will not open the power generating circuit.
In the solar cell module according to the prior art, the bypass diode and the solar cell are both located on a substrate and form a circuit via a metal conducting layer. Wires are soldered on the metal conducting layer for outputting the current of the solar cell module and thus forming a complete circuit.
Nonetheless, this structure occupies a great area because in addition to the solar cell and the bypass diode, an extra region should be reserved as the wire soldering area, which forces the vendors of the solar cell power generating system to adopt a larger substrate. In other words, a portion of the larger substrate has only the function for soldering the wires and makes no significant contribution on power generation. In FIG. 1, the current flowing through the bypass diode 30 via the first pin 301 (not shown in the figure) is guided to first wire 501 passing the first metal conducting area 201. On the other hand, by contacting the second pins 302 from the side with the second metal conducting area 202, the current flowing through the second pins 302 can flow to the second wire 502 via the second metal conducting area 30. In this architecture, the metal conducting layer 20 is required for the bypass diode 30 for guiding the currents to the first wire or the second wire 501, 502. In a solar cell power generating system, each small piece of area is precious and should be reserved for power generation. Thereby, the disposal of the soldering areas is undoubtedly a design raising the cost but unbeneficial to power generation.
Accordingly, how to solve the waste brought by the wire soldering areas is an important issue of the solar cell power generation field.